Check Chetan Comment
https://www-secure.symantec.com/connect/forums/virus-definitions-0#comment-10478541
File-based AV - Updated daily (with SEP's Multiple Daily Definitions, certified content is typically released three times a day Monday through Friday; one time per day on weekends).
Network-Based Protection (IPS)- SEP Security Updates (SU) are generally updated on Weekdays (M-F - no releases scheduled for weekend or major holidays in the United States).
Behavior-Based Protection / Proactive Threat Protection - There is no set schedule. The article linked below contains additional information.
Reputation-Based Protection (Insight) - Continually updated as it is a cloud based detection.
For additional details please visit: http://www.symantec.com/security_response/definitions.jsp
How often are Endpoint Protection definitions for IPS, SONAR, and Download Protection released?
http://www.symantec.com/docs/TECH178271
Rapid release defintion is updated on daily bases.
I recommend you to update the Rapid release defintion.
http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=rr